Rapid assessment of the Indian mackerel Rastrelliger kanagurta fishery in Kenya’s coastal waters

Abstract

The Indian mackerel, Rastrelliger kanagurta is a highly migratory epipelagic species in the family Scombridae. The species plays a significant role in supporting the food security and livelihoods of coastal communities in the Western Indian Ocean. The exploitation status of R. kanagurta in Kenya’s waters is uncertain. This study evaluated the R. kanagurta fishery using available catch data collected from 2014-2015 and 2017-2020. The study described the catch dynamics and utilized a suite of length-based approaches to derive diagnostic indicators of the exploitation status. Four gear types were documented that target the species, dominated by ring nets (79%) and reef seines (11%). Catch rates and selection patterns of fishing gears targeting R. kanagurta varied between gear types. Reef seines caught the highest proportion (80%) of immature R. kanagurta below size at maturity (L50), while the lowest (0%) was by handlines and set gillnets. There were statistically significant differences in the proportion of R. kanagurta caught below L50 between gear types and years. Overall, the spawning potential ratio (SPR) was within optimal levels at 0.48 and was above the target reference point of 0.4 during all years. The assessment provides a case study for the rapid evaluation of fishery performance for Kenya’s data-limited fisheries